SYNTHESIS OF DISCRETE-TIME NONLINEAR FEEDFORWARD FEEDBACK CONTROLLERS

This work concerns the synthesis of discrete-time feedforward/feedback control systems for general nonlinear processes with stable zero dyna mics. Depending on the process under consideration, the derived feedfo rward/feedback controllers can completely eliminate the effect of meas urable disturbances and produce a prespecified linear response with re spect to a reference input, or provide integral-square error optimal r esponse to step changes in the disturbances and a prespecified linear response with respect to a reference input. In either case, the develo ped feedforward/feedback controllers allow for the asymptotic rejectio n of unmeasurable disturbances. These controllers are derived within t he globally linearizing control framework, first underfull state infor mation and then in the absence of state measurements. The internal sta bility of the closed-loop system is addressed. The derived controllers are interpreted from a model-predictive point of view, and their conn ections with the feedforward internal model control and the model algo rithmic control are established. The theoretical results are illustrat ed through a continuous stirred-tank reactor example.